On-board electrical system/power supply
Electrical system
19
Introduction of smart fortwo electric drive (3rd Generation) • Model Series 451
Shutting off the high-voltage on-board
electrical system
The high-voltage on-board electrical system must
be able to be shut off in an accident or for
servicing. For this purpose, the high voltage
output of the high-voltage battery can be discon-
nected from the high-voltage on-board electrical
system by contactors which are actuated by the
battery management system control unit.
The pyrofuse and Service Disconnect plug are
connected in series in the control line of the
contactors.
Accident
In the event of an accident, the high-voltage on-
board electrical system can either be shut off by
the high-voltage crash sensor control unit or the
restraint system control unit.
Shutoff by restraint system control unit
If the restraint system control unit triggers the
airbags in an accident, the pyrofuse in the control
line of the contactors is also triggered. The
control line is then physically disconnected. The
high-voltage output remains irreversibly deacti-
vated.
Shutoff by high-voltage crash sensor control
unit
The high-voltage crash sensor control unit is
located under the left-hand seat on the vehicle
floor. It shuts off the high-voltage on-board elec-
trical system in the following conditions:
• During charging: in the event of a stationary
crash
• During driving operation: in the event of a
rollover
The high-voltage on-board electrical system and
the high-voltage crash sensor control unit are
also active during pre-conditioning on a parked
vehicle. The high-voltage crash sensor control
unit causes the battery management system
control unit to shut off the contactors by means of
a signal on the CAN bus. This shutoff of the high-
voltage on-board electrical system is reversible.
i Note
The procedure for deenergizing the system is
described in the chapter "Deenergisation" as of
page 48.
Service
During servicing, the control line of the contac-
tors is physically disconnected by disconnecting
the Service Disconnect plug. The high-voltage
output remains permanently deactivated and can
no longer be switched on by the battery manage-
ment system control unit.
To Next Page
Loading...
Need help?
General
